President Bush’s choice of John Bolton to represent the U.S. at the United Nations was meant to roil the diplomatic world. The man is outspoken in his derision of the international organization and famous for his fiery language against countries that oppose American wishes. But there is a saying in Washington that you meet on the way down all the people you stepped over on the way up. And that is what appears to have put Senate approval of the controversial nomination in jeopardy.

In the seven weeks since Bush named him, Bolton has been getting reacquainted with some of those people he offended during a 24-year career in the Federal Government. They are, among others, the two intelligence analysts who claim that as a senior State Department official during Bush’s first term, Bolton tried to have them fired or reassigned when they disagreed with him; the foreign-aid worker who says Bolton, then a private attorney, chased her down a Moscow hotel hallway in 1994 in an effort to intimidate her; and the former U.S. ambassador to South Korea who complained that Bolton had misled the Senate Foreign Relations Committee by suggesting that the ambassador had approved an incendiary speech Bolton made about North Korea in 2003.

Such charges have raised new questions about Bolton’s treatment of subordinates, his pressure on intelligence analysts to support his views and the candor of his testimony. They also broke what had been unanimous G.O.P. support in the Senate for Bolton’s nomination. The 10 Republicans on the Senate committee seemed ready to pass his nomination on to the full chamber until one of their own unexpectedly balked. “My conscience got me,” said Ohio Republican George Voinovich in a declaration, rare for its spontaneity in political Washington, that put Bolton’s confirmation on hold last week.

But the hardest blow may have come two days later from Colin Powell, when word leaked with conspicuous speed across the capital that the former Secretary of State had privately conveyed his doubts about Bolton to two other wavering G.O.P. Senators. Powell reportedly praised Bolton’s intellect and his work in some areas but told the Senators he had been troubled by the way Bolton had treated subordinates who did not agree with him. “Powell still carries a lot of weight with some of these guys,” said an aide to a top Senate Republican who supports Bolton’s nomination. And with the vote on Bolton’s nomination pushed off until May 12, committee Democrats have plenty of time to investigate the allegations against him–and field new ones. “If this keeps up,” says the G.O.P. official, Bolton “won’t survive.”

It’s often the steady drip-drip of accusations that ultimately undermines embattled Washington nominees. But what’s surprising about Bolton’s precarious situation is that he may be undone more by the charges that he’s a bully toward colleagues and underlings than by his strongly held conservative views about U.S. foreign policy and international institutions like the U.N. “We can’t argue that this guy is unfit just because he’s said mean things about the U.N.,” conceded a top Senate Democrat. “Don’t forget, most Americans agree with him.” Though troubling to some Republicans, even allegations that Bolton has a tendency to exaggerate intelligence to suit his ideological preconceptions–and intimidate analysts who challenge him–did not seem enough to persuade them to risk the wrath of the Bush White House by opposing him.

But tales of Bolton’s ferocious management style seemed to strike a toxic note. One charge came from Melody Townsel, who dispatched an impassioned e-mail to the committee about her encounters with Bolton while working for a private subcontractor on a 1994 U.S. Agency for International Development (AID) mission in the former Soviet republic of Kyrgyzstan. Townsel says she wrote a letter to AID officials complaining about the lack of funds for the project from the contractor, a company that had hired Bolton as a lawyer. “Within hours after dispatching that letter,” Townsel told the committee, “my hell began. Mr. Bolton proceeded to chase me through the halls of a Russian hotel–throwing things at me, shoving threatening letters under my door and generally behaving like a madman … Mr. Bolton then routinely visited [my hotel] to pound on the door and shout threats.” Later, Townsel says, Bolton falsely told AID and other U.S. officials that she was under investigation for misuse of funds. Democrats and TIME have found witnesses to corroborate parts of Townsel’s story. Republicans point out that she is a Democrat who was a member of the Dallas chapter of Mothers Opposing Bush during the 2004 campaign. Townsel tells TIME she did public relations work for the organization but insists her story about her encounter with Bolton–which “had a tremendous, terrible impact on me”–is true.

Bolton faces less partisan accusers as well. Nearly 60 retired diplomats, many of whom served under Republican Presidents, signed a letter to the committee opposing Bolton’s confirmation. Frederick Vreeland, a former ambassador to Morocco who worked under Bolton when both were senior State Department officials in the Administration of Bush’s father, sent an e-mail obtained by TIME to top committee Democrat Joseph Biden, saying Bolton “dealt with visitors to his office as if they were servants with whom he could be dismissive, curt and negative.”

Bolton’s supporters acknowledge he has a temper and may not always have treated subordinates kindly, but they say Democrats are using Bolton’s abrasive personality as an excuse to kill a nomination they oppose on ideological grounds. “If being occasionally tough and aggressive and abrasive were a problem,” chided Vice President Dick Cheney, “a lot of members of the United States Senate wouldn’t qualify.” Said Danielle Pletka, vice president for foreign and defense studies at the American Enterprise Institute, a conservative think tank where Bolton once worked: “This is not the outrage of sincere grownups over the malfeasance of a senior executive. John is not about making the world safe for cocktail parties.”

But opponents say the problem is more than a matter of bad manners and bruised egos: Bolton’s pattern of intimidation, they claim, was also aimed at distorting vital intelligence. Government sources tell TIME that during President Bush’s first term, Bolton frequently tried to push the CIA to produce information to conform to–and confirm–his views. “Whenever his staff sent testimony, speeches over for clearance, often it was full of stuff which was not based on anything we could find,” says a retired official familiar with the intelligence-clearance process. “So the notes that would go back to him were fairly extensive, saying the intelligence just didn’t back up that line.”

Those episodes, sources say, frequently involved statements Bolton wanted to make about the malign intentions and weapons capabilities of Cuba and North Korea. Two analysts–one at the State Department and the other at the CIA–told the committee they had run afoul of Bolton in 2002 after they warned that he was making assertions in a speech about Cuba’s weapons programs that could not be backed up by U.S. intelligence. Bolton, they said, tried to have them removed from their jobs. Witnesses say that after one of the analysts, Christian Westermann, wrote an internal memo warning of Bolton’s embellishments, he was summoned to Bolton’s office and subjected to a finger-wagging tirade. Westermann’s boss at the time, Carl W. Ford Jr., told the committee in a public hearing two weeks ago that he considered Bolton “a serial abuser” of underlings and “a quintessential kiss-up, kickdown sort of guy.”

Fulton Armstrong, then head of the Latin American division at the CIA’s National Intelligence Council, told the committee in private that he was subjected to similar mistreatment by Bolton after he raised objections to the contents of the Cuba speech. Bolton denies pushing to get anyone fired, and his supporters point out that neither Westermann nor Armstrong lost his job. Bolton testified that he did ask to have Armstrong reassigned because he had “lost confidence” in him, although he never worked with him or even met him.

Committee Democrats have investigated another charge that Bolton tried to have a State Department lawyer who disagreed with him removed from a case in October. The dispute involved a request by a Louisiana-based company for a waiver to import goods from a Chinese company on which the U.S. had recently imposed sanctions. Sources familiar with the incident tell TIME that Bolton, who opposed the waiver, became angry when he learned that the State Department’s legal division supported it. He went to William Taft, the department’s top lawyer, to demand that Taft’s subordinate be taken off the case. A witness to their discussion described Bolton as “shouting” and “yelling” at Taft. “But that was nothing unusual,” a former official who was present tells TIME, “because John was always a strong friend of his own opinion.” Taft stood by the lawyer and refused to remove him.

Democrats say they are also troubled by the fact that on 10 separate occasions over the past four years, Bolton asked the super-secret National Security Agency (NSA) to divulge the names of U.S. citizens whose conversations with foreigners were intercepted and transcribed. While some intel officials dismissed Bolton’s requests as routine, others took a darker view. One former senior NSA official tells TIME he was “shocked” to learn Bolton had requested the names of Americans deleted from such intercepts. “It’s extremely unusual for someone at Bolton’s level to make those requests,” the official says. “The NSA shouldn’t be handing these over. They’re not paid to hand around gossip.” Senate sources tell TIME that Jay Rockefeller, the top Democrat on the Senate intelligence committee, has asked the NSA to turn over the Bolton intercepts, including the American names that interested him.

The biggest danger facing Bolton is suspicion that he deliberately misled Senators in his public testimony defending himself against these challenges. Already they have statements from Thomas Hubbard, who was President Bush’s ambassador to South Korea during his first term, saying Bolton misrepresented Hubbard’s views about the bitingly anti–North Korea speech Bolton gave in July 2003, just days before the launch of delicate six-nation talks aimed at persuading Pyongyang to give up its nuclear-weapons program. The speech–in which Bolton vilified Kim Jong Il as a “tyrannical dictator” and said life in North Korea was a “hellish nightmare”–infuriated the North Korean government and, U.S. diplomats say, nearly torpedoed the talks. In defending his undiplomatic language, Bolton told Senators that it had been cleared by relevant officials and that Hubbard had personally thanked him for it.

Hubbard contacted the committee last week and said he had, in fact, opposed the speech and had thanked Bolton only for making some specific minor changes to it that Hubbard had requested. According to a memo obtained by TIME describing Hubbard’s interview last Friday with committee Republicans, the former ambassador “says he strongly disagreed with the tone of the speech, especially at the sensitive time in the negotiating process, and asked Mr. Bolton to tone it down. He did not.” Retired Ambassador Charles Pritchard, who was then special envoy for negotiations with North Korea, tells TIME he never approved Bolton’s speech either. “I had a chance to see [a draft of] the speech in advance and refused to clear it,” says Pritchard.

Despite the uproar last week, White House officials insisted President Bush has no intention of withdrawing Bolton’s nomination. The President stoutly called Bolton the “right man at the right time” to badger a sclerotic U.N. into reform. “There is going to be a more forceful approach in the coming days to make this a debate about the United Nations and not John Bolton,” says a senior White House official. “He has rough edges, but that’s what you want right now.”

In the meantime, Bolton’s confirmation looks far from assured. That has not prevented the nominee, however, from moving through his to-do list. Government sources tell TIME that after he was nominated in early March, Bolton requested that all American employees of the U.S. mission to the U.N. submit their résumés for review. The move cast a chill over the operation, where some saw it as presumptuous. It may also have been premature.